Resilient support and centering arrangement for the electrodes of electric discharge tubes



Jan. 17, 1950 e. H. P. ALMA RESILIENT SUPPORT AND CENTERING ARRANGEMENT FOR THE ELECTRODES OF ELECTRIC DISCHARGE TUBES Filed May 7, 1948 AGIN'I' Patented Jan. 17,1950

RESILIENT SUPPORT AND CENTERING AR- RANGEMENT FOR THE ELECTRODES OF ELECTRIC DISCHARGE TUBES Gerrit Hendrik Petrus Alma, Eindhoven, Netherlands, assignor to Hartford National Bank and Trust Company, Hartford, Gonrn, 'as trustee ApplicationMay 7, 1948, Serial No. 25,661 In the Netherlands August 27, 1947 2 Claims. 1

This invention relates to an electric discharge tube and more particularly to the centering members for the electrodes of such a tube.

In general the electrodes are centered at least at one end by means of one or more plate-shaped insulating members usually consisting of mica. To prevent clearance of electrode parts e. g. supporting wires or the end of an indirectly heated cathode, which are supported in apertures of these members, it has been proposed to superpose two or more plateshaped insulating members in such manner as to clamp the said electrode parts in the apertures or between these members. However, these known constructions have the disadvantage that resilient clamping is difficult to ensure. This method of clamping is very desirable in view of the thermal expansion of the electrodes and for avoiding microphonic disturbances. As a rule, consequently, these members must satisfy stringent requirements, since in manufacture very small tolerances, in regard to their size. are allowed to prevent the clamping from being too loose or too tight.

According to the present invention the aforesaid effect and resilient clamping are ensured without experiencing the disadvantage of the necessity to maintain very small tolerances in processing the component parts.

In an electric discharge tube comprising an electrode system, in which two or more electrodes are centered by means of at least one plateshaped insulating member consisting of an assembly of two or more parts partly overlapping each other and are clamped between these parts, this clamping is effected, according to the invention, by furnishing one of the component insulating parts with tongues, some of which each engage part of an electrode in one direction, and one or more other tongues resiliently engage parts of an other electrode in the opposite direction, at least one of the tongues having such a length that, when it is bent out of the plane of the plateshaped part, it engages the associated electrode part. Since, consequently, the plate-shaped part engages electrode parts in two directions, it clings to it, whilst the total pressure of the tongues in both directions is in equilibrium and consequently always the same. This pressure depends upon the resilience of the slanting tongue(s), so that this pressure can easily be kept within the desired limits. Moreover, the size of the tongues is not bound to narrow limits, since a difierence in length of the tongues is compensated by curvature of the resilient tongues to a greater or smaller degree.

In order that the invention may be more clearly understood and readilycarried into efi'ect, it will now be described more fully with reference to the accompanying drawing, given by way of example.

In this drawing Fig. 1 represents a resilient part of a centering member according to the invention, Fig. 2 and 3 being detail views.

In Fig. 1 the reference numeral i denotes the cross-section of an indirectly heated cathode, 2 denoting the cross-section of the supporting rods for the first grid, and '3 and 4 denoting the supporting rods i'or the second and third grid respectively. Since the first grid acts as a control-grid it is imperative that this grid should be so centered with respect to the cathode I as to be immovable and free from vibration. The electrode supports are centered in an apertured mica disc 5 through the apertures of which the supporting wires and the cathode end pass in a known manner. Since, in general, the apertures of this mica member 5 will not make a close fit, the supporting rods engaging these apertures may exhibit a little clearance. According to the invention a mica plate 6 furnished with tongues 1 and 8 (Fig. 2) is placed on the member 5. The tongue I has a comparatively great length and engages the cathode, whereas the short tongues 8 engage the supporting rods 2 in the opposite direction. Owing to its considerable length the tongue I exhibits considerable resilience in a direction at right angles to the plane of the member 6, and since the length of the tongue 1 is such that the tongue occupies an oblique position on placing the member 6 on the member 5 a satisfactory yielding spring effect is ensured. The pressure exerted by the tongue I is compensated by that of the tongues 8 so that the member 6 is in. equilibrium. Owing to the oblique position of the tongue 1 the said member 6 does not tend to move upwards. Since the cathode is pressed against the side of the aperture in the member 5 opposite the tongue I the size of this aperture in the other directions is of no importance. For this reason the aperture 9 (Fig. 3) is square, which is advantageous for introducing the cathode. It has been found that the use of member 6 according to the invention yields a flexible and resilient clamping of the said electrode parts, whilst microphonic disturbances, for instance due to mutual vibration of the cathode and first grid, are highly reduced. Owing to the resilience of the tongue 1 the rods 2 and the cathode end I may expand practically unhindered on heating.

Although only one example has been given, it will be appreciable that also other shapes of the member fall under the scope of the invention. Thus, for instance, a plurality of tongues i may be used which may also engage the supporting wires for the other grids.

What I claim is:

1. An electric discharge device comprising a plurality of spaced, parallel rod members in spaced relationship, a first plate member of electrically insulating material provided with a plurality of apertures in spaced relationship conforming to the spacing of said rod members and engaging said rod members, and a second plate member of resilient electrical insulating material, said second plate member being provided with a central aperture and resilient rib portions inwardly extending from opposite walls of said aperture, said second plate member being positioned on said first plate member with two resilient rib portions extending from one wall and each engaging one of said rod members on the side adjacent said rib portions and a third resilient rib portion extending from the opposite wall portion andvpositioned centrally of said two rib portions and engaging the adjacent side of another of said rod members, said third resilient rib portion being flexible in a plane normal to the plane of said second plate member.

2. An electric discharge device comprising a cathode, a plurality of spaced, parallel rod members in spaced relationship, a first plate member of electrically insulating material provided 4 with a plurality of apertures one of which apertures is in the form of a square, said aperture being in spaced relationship the spaced relationship conforming to the spacing of said rod members and the aperture engaging said rod members, and a second plate member of resilient electrical insulating material, said second plate member being provided with a central aperture GERRIT HENDRIK PETRUS ALMA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 7 1,974,086 Smith Sept. 18, 1934 2,048,257 Glauber July 21, 1936 2,072,638 Jobst Mar. 2, 1937 2,140,441 Clark Dec. 13, 1938 FOREIGN PATENTS Number Country Date 506,386 Great Britain May 18, 1939 

